Method of making hollow forged valves



Feb, 4,, 1936 w. SCRIMGEOUR METHOD OF MAKING HOLLOW FORGED VALVES Filed Dec. 19, 1934 2 Sheets-Sheet 1 Feb. 4, 1936. w scRlMGEQUR 2,029,507

METHOD OF MAKING HOLLOW FORGED VALVES Filed Dec. 19, 1954 2 Sheets-Sheet 2 Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE METHOD OF MAliliNLG HOLLOW FORGED VES William Scrimgeour, Washington, D. G. Application December 19, 1934, Serial No. 758,306

8 Claims. (Cl. 29-156.7)

This invention relates to methods of makin hollow forged valves, and more particularly poppett valves for use in automobile and airplane engmes.

In my prior application, Ser. No. 701,210, filed Dec. 6, 1933, now Patent No. 1,992,245, I have described and claimed methods of forming one-piece hollow valves by upsetting the closed end of a blank and working down the remainder of the blank to form an elongated stem.

Objects of this invention are to provide economical methods of forming hollow valves with relatively large diameter heads from small diameter blanks. A further object is to provide valves, and methods of forming the same, with integral heads and stems, and with a hardened, wear-resisting surface for contact with a valve seat. A further object is to provide a method of forming a pair of hollow forged valves from a single blank.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawings in which:

Fig. 1 is an elevation of a cylindrical blank;

Figs. 2 to 6, inclusive, are longitudinal central sections illustrating successive steps in the formation of a valve from the cylindrical blank of Fig.

Fig. 7 is a side elevation of a valve at the close of the forging operations;

Fig. 8 is a central section through a die and blank, illustrating the transformation of the blank from the Fig. 2 to the Fig. 3 form;

Fig. 9 is a transverse section through swaging dies such as used for imparting the final form to the valve head; I I

Fig. 10 is a longitudinal fragmentary section through a modified valve structure;

Figs. 11, 12, and 13 are longitudinal central sections illustrating progressive steps in the formation of a hollow valve having a reinforced wearing surface;

Fig. 14 is an elevation of a cylindrical blank for forming a pair of valves;

Fig. 15 is a view through swaging dies and the blank after the first operation; and

Fig. 16 is a fragmentary longitudinal central view illustrating the blank after further operations. In the drawings, the starting blank I is a steel cylinder having a diameter less than that of the finished valve head and substantially greater than that of the finished stem, the length of the blank being materially shorter than that of the finished valve. The blank is counterbored, as indicated at 2, to ave a closed endor wall 3 which is much thicker than the desired wall thickness of the valve head. The next step is the transformation of the blank into the form illustrated in Fig. 3 by punching the heated closed end of the blank in dies 4, 4 to round off the closed end 5 by displacing the excess end wall material of the blank rearwardly along the punch 5. The dies 4, 4 are preferably countersunk to form a small central lug ,6 at the extreme end of the blank, this lug providing material which may be slotted to 10 provide a kerf for receiving the end of a screw driver or other valve-grinding tool.

The punching of the heated blank to impart a rounded contour to the closed end is entirely practical as the slightly tapered punch 5 is quick- 15 ly withdrawn from the heated end of the blank before it can expand and become locked to the blank.

This general process of forming a rounded end on the blank is described in my prior application. 20 The present process is characterized by the for mation of the annular bead or ring I at the base of the semi-spherical head. The bead I is readily formed by the flow of thehot metal during the described punching operation. The purpose 25 of the bead is to provide a larger diameter section, for a given size of blank, which is available for the formation of a larger diameter head.

Attention is directed to the fact that the punching or die-shaping of the end of the blank pref- 30 erably leaves the thickness of the rounded'end wall, 1. e., the section A of the blank, somewhat less than that of the cylindrical wall of the hollow blank.

The portion Bof the blank, Fig. 3 immediately 35 back of the head 1 is then heated and forged in swaging dies to form the end of the blank to the shape of an approximately spherical ball having a central band or head, by reducing the section adjacent the ball end to the approximate diameter 40 of the finished valve, Fig. 4. During this forging operation, the wall thickness at the rear of the ball end will be reduced somewhat as the metal is displaced inwardly and rearwardly by the repeated blows of the swaging dies.

The remaining or large diameter portion of the blank is then heated and worked down, for ex-- ample in another set of swaging dies or hammers, to form an elongated, hollow stem, as shown in Fig. 5. At intervals during, or at the close of this 50 operation, the bore of the stem may be reamed.

The ball head is then heated and upset or shaped to its final form, Figs. 6 and 7, by placing the blank in the longitudinally split die members 9, 9 and forcing the movable die l0 against the 55 ball end. The dies are so shaped that this operation imparts the final form to the forged blank. The metal of the heated ball end is readily and substantially uniformly displaced axially and laterally to form a symmetrical hollow head of uniform wall thickness at the end of the hollow stem.

The metal of the bead 1 forms the rim portion of the valve head and thus increases the diameter of the valve which can be formed from a given blank. The possibility of cracking or checking at the inner junction of the upper and lower sections of the valve head limits the head diameter that can be obtained from stock of a given size. In the absence of this bead, round bar stock of 1 inch diameter would be required for the manufacture of a 3 inch valve. A sound valve of the same diameter may be readily and more economically produced from one inch stock by forming a bead 'I of approximately A inch thickness at the rim of the ball-shaped end of the blank, Fig. 3. These figures are to be understood as illustrative only, since the invention is not restricted to any particular diameter of the valve head or of the stock.

The blank may then be machined, in the usual manner, to form the seat-engaging surface H and to cut a kerf l2 in the projection 6. Appropriate grooves may be cut in, the end of the stem or it may be otherwise finished to receive a collar or spring seat and a bearing block for engagement by the valve tappet. If desired, the hollow valve may be partially filled in known manner with a. heat-exchanging material for facilitating the cooling of the valve. The final forging operations may be varied somewhat, in accordance with the desired final form of the valve, as they may be so conducted as to leavethe forged blank in the most convenient shape for the machining operations.

As shown in Fig. 10, the working down of the stem portion of the blank may be so performed, if desired, that the bore is completely closed to leave a hollow head I3 at the end of a substantially solidstem l4.

While I have described a succession of operations which I believe to be preferable, it will be apparent that there is some latitude in the several operations. For example, for valvesof some sizes and when employing some materials, it may be convenient and economical to cast a blank in the form shown in Fig. 2. It is also possible to machine a blank to the form shown in Fig. 3, but, in general, the described punching or die-shaping operation for obtaining a blank of this form will be more economical than a machining operation. The process may be applied to the formation of poppet valves which differ in design from the form illustrated and materials other than steel may be employed in forming one-piece hollow valves.

A harder, wear-resisting surface may be provided for contact with the valve seat by the method which is shown graphically in Figs. 11 to 13, inclusive. After shaping the blank I to form the semi-spherical end and projecting bead I, a layer l5 of harder steel, a cobalt alloy or the like is welded to the blank along the lower surface of the bead and the adjacent surface of the cylindrical blank section. This harder metal layer will fiow during the succeeding swaging step to form a smooth fillet I5 between the bead I and the inner portion of the globular end of the blank, Fig. l2. Preferably, however, the layer of harder metal I5 is welded upon the blank after globular head is formed and the stem has been worked down, i. e., when the blank has the form illustrated in Fig. 5. The advantage of applying the harder metal atthis stage is that there is only one working of the welded joint. When the head is forged in the dies, such as those of Fig. 9, the hard metal I5 is accurately shaped substantially to its final form. This seating surface is very hard and, for some uses, will not require grinding. When greater accuracy is required, the finishing step is quite economical as only a small amount of material need be removed.

An alternative procees for forming the valves is illustrated in Figs. 14 to 16. A cylindrical bar or rod I6 of a diameter substantially smaller than the valve head is first nipped at its center to form a short, small diameter section I! which may be bordered by a somewhat enlarged section I8 when the forging operation is performed by swaging dies I9. and bead 2! are then formed by swaging between dies which have central'ribs conforming to this outline. It is to be noted that the initial formation of the short connecting section l'l facilitates the shaping of the rounded ends without substantial loss of metal. If it were attempted to form the rounded surfaces 20 in a single set of forging dies, the resistance to lateral flow would produce a long strip of metal between the two valve blanks. The opposite ends of the blank are bored out at the close of the swaging operations, as shown by the broken lines, to leave end walls of approximately the thickness of the desired end wall thickness of the finished valves. The portions just beyond the beads 2| are then swaged down, and the stems are worked down in the manner described in connection with Figs. 4 and 5. Alternatively, the blank may be separated by cutting the strip I! to provide two valve units substantially like those of Fig. 3.

It is to be understood that various changes may be made in the described series of operations and in the form of the valves without departing from the spirit of my invention as set forth in the following claims.

I claim:

1. The method of forming a hollow poppet valve from'a metal blank having a diameter intermediate that of the desired head and stem diameters, which comprises shaping the outer surface of that portion of the blank which is to constitute the outer head wall to the form of a semi-spherical surface having a projecting bead at the diameter thereof, reducing the diameter of the blank at the portions adjacent said bead, and pressing the said portions of the blank to form a valve head having the metal of said bead at the rim thereof.

2. The method of forming a poppet valve from a metal blank having a diameter intermediate that of the desired head and stem diameters which comprises forming the closed end of a tubular blank to the form of a semi-spherical shell having a projecting bead at the diameter thereof, reducingthe diameter of the blank adjacent said bead to shape the end to approximately the form of a ball having a circumferential bead, working down the tubular portion of the blank to form an elongated stem, and pressing the ball portion to the approximate form of the valve head.

3. The method of forming a poppet valve of the hollow head type from a tubular blank having one closed end, which method comprises forming a tubular blank with one closed end,

h in

blank, working down the blank adjacent the bead working the closed end to substantially hemispherical form with a projecting bead at the junction of the closed end and'the tubular portion, working down the tubular blank adjacent said head to form an approximately globular hollow head, working down the remaining tubular portion to form an elongated stem, and compressing the said hollow head portion axially of the stem to form a hollow head of relatively large size.

4. The method as claimed in claim 3, in combination with the step of reaming out the elongated stem to provide a bore communicating with the hollow head.

5. The method of forming a poppet valve which comprises forming a tubular blank with a relatively thick wall at one end thereof, pressing the end wall axially to shape the closed end-of the blank to a rounded form joined to the tubular portion of the blank by a bead, working down the adjacent tubular portion of the blank to leave a substantially globular head at the closed end of the blank, working down the remaining tubular portion of the blank to the desired stern size, and dieshaping the globular end to the form of the desired hollow valve head.

6. In the manufacture of poppet valves by the process which includes dieforging the substantially globular head of a blank to form a hollow valve head, the method of increasing the maximum diameter valve which may be made from stock of a given diameter which comprises/the steps of working the stock to produce a tubular.

blank having one substantially hemispherical end wall and a circumferential bead at the junction of the end wall and the tubular portions of the to form an approximately globular end to the blank, and die-forging the globular end to form a hollow valve head.

'7. In the process of forging a valve, the step which comprises shaping the closed end portion of a hollow cylindrical metal blank to the form of a hemisphere with a projecting head at the junction of the hemisphere and the cylindrical portion of the blank, reducing the diameter of the cylindrical portion adjacent said bead to form an approximately. globular end, working down the cylindrical portion of the blank to form an elongated stem, welding a harder metal to the adjacent surfaces of the bead and blank at the stem side of said head, and die-forging the globular end axially of the stem to form a valve head having the harder metal at the seating surface thereof. a

8. In the process of forming a pair of hollow valves, the steps which comprise reducing the central portion of a cylindrical rod blank to form a short, small diameter connecting section, shaping the blank adjacent said section to the form of opposed hemispherical surfaces having projecting beads connecting the same to the adjacent cylindrical portions of the blank, counterboring the opposite ends of the blank to provide end walls ofthe approximate thickness of the valve head, reducing the diameter of the cylindrical portions 'of the blank adjacent said beads,

working down theremaining cylindrical portions to form elongated'valve stems, and pressing the rounded ends of the two sections of the blank to form valve heads. 1

WILLIAM SCRIMGEOUR. 

